Composition and method for diagnosing auto-immune hepatitis

ABSTRACT

A composition and method for the diagnosis of autoimmune hepatitis. The composition, which contains SLA antigens detects soluble liver antigen (SLA) auto-antibodies, which occur in sera of patients suffering from chronic hepatitis.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a composition and method for diagnosing auto-immune hepatitis, which use an immune reaction to detect soluble liver antigen (“SLA”) auto-antibodies.

[0002] Auto-immune hepatitis (AIH) is a chronic inflammation of the liver that when left untreated leads to cirrhosis, but when treated has a very good prognosis. For this reason, a timely diagnosis is important. It is estimated that 5% of all patients in Western countries who have chronic hepatitis have AIH. At the present time, there is no specific diagnostic test for AIH. Rather the diagnosis for AIH is undertaken by a plurality of diagnosis, such as excluding viral hepatitis, recognizing [hyper] immunoglobulinaemia, recognizing the tissue type (HLA type), and detecting auto-antibodies. Auto-antibodies are found in about 90% of patients with chronic hepatitis, and most of the detectable auto-antibodies are also present, at least in low titers, in other inflammations of the liver as well. In particular, these auto-antibodies are antibodies to nuclear antigens (ANA) and unstriated muscles (SMA), as well as the very rare antibodies to cytochrome p450 (LKM). SLA auto-antibodies were described for the first time in 1987 (Manns M. et al., Lancet 1987; 1:292-4). Tests have shown that SLA auto-antibodies occur in about 25 to 30% of patients having AIH, but hardly ever occur in patients having other diseases, including other auto-immune diseases (Lohse A. W. et al., Z. Gastroenterol 1995;33:527-33). Detecting SLA auto-antibodies therefore provides a significant diagnostic procedure for recognizing AIH.

[0003] The present invention is directed to use and detection of SLA antigens, which are a prerequisite for developing a specific immunoassay for detecting SLA auto-antibodies in patients' sera. Previous methods known in the art could not detect such SLA auto-antibodies in patients' sera. Liver cytokeratins 8 and 18 were described in 1990 as target antigens of the SLA auto-antibodies (Journal of Hepatology, 1990; 11: 232 to 239), however, these findings were never confirmed, and were even refuted (Wies I. et al., Z. Gastroenterol. 1998;36:93).

SUMMARY OF THE INVENTION

[0004] The invention is directed to a composition for detecting the presence of SLA auto-antibodies in blood serum, said composition comprising an antigen that is recognized by SLA auto-antibodies. In particular the invention is directed to antigens having amino acid sequence SEQ ID NO. 1, SEQ ID NO. 2, or antigenic derivatives thereof. Another embodiment of the invention is a purified protein or polypeptide recognized by SLA auto-antibodies. In a perferred embodiment of the invention the purified protein has the amino acid sequence SEQ ID NO. 1, SEQ ID NO. 2, or is an antigenic derivative thereof, or is a fusion protein containing either SEQ ID NO. 1, SEQ ID NO 2, or antigenic derivatives thereof. In another aspect of the invention, there is disclosed a cDNA having a nucleotide sequence that codes for an antigen recognized by SLA auto-antibodies in blood serum. In a preferred embodiment of this aspect of the invention the cDNA codes for an antigen having the amino acid sequence SEQ ID NO. 1, SEQ ID NO. 2, or an antigenic derivative thereof.

[0005] Another aspect of the invention is directed to a method of detecting the presence of SLA auto-antibodies in a blood sample by binding the composition of the invention to a matrix, detecting the binding of SLA auto-antibodies bound to the antigens in the composition, and correlating such binding to the presence of SLA auto-antibodies in the sample. Examples of suitable methods in which the present compositions can be used to detect SLA auto-antibodies in blood include immunoassays such as, but not limited to, radioimmunoassay, chemiluninesence immunoassay, immunoblot assay, enzyme assay and inhibition immunoassay.

DETAILED DESCRIPTION OF THE INVENTION

[0006] The present invention relates to a composition and a method for diagnosing auto-immune hepatitis, by enabling one to detect in the blood serum of a patient, antibodies to two proteins or polypeptides (SLA antigens), which antigens wholly or partially contain the amino acid sequence corresponding to SEQ ID NO. 1 or SEQ ID NO. 2 or antigenic derivatives of the SLA antigens, which are recognized by SLA auto-antibodies. These polypeptides are referred to as SLA-1 and as SLA-2. One embodiment of the invention is directed to synthetic or natural variants of SLA-1 or SLA-2, or sythetic or natural variants of partial or incomplete polypeptides of SLA-1 or SLA-2, which correspond wholly or partially to the amino acid sequences or antigenic derivatives thereof and are likewise recognized by SLA auto-antibodies.

[0007] In a preferred embodiment, the peptides of the invention are fusion proteins. Such fusion proteins can be made by known methods in the art (Maniatis, T. et al., Molecular Cloning, 1982: 412-430).

[0008] Another embodiment of the invention is directed to cDNA, which encodes a natural or synthetic variant of one of the SLA antigens SLA-1 or SLA-2, having a nucleotide sequence corresponding to SEQ ID NO. 1 or to SEQ ID NO. 2 or to antigenic derivatives thereof. The cDNAs are present as two spliced variants, the longer of these (SEQ ID NO. 2) having an insertio of 156 nucleotides. SLA-1 and SLA-2 have similiar nucleotide sequences, except that SLA-2 contains a 156 nucleotide insert.

[0009] SLA-positive sera, i.e. SLA auto-antibody containing sera, produces a double band on a Western blot when probed with the SLA antigens. The double band measures 50 kDa, which corresponds to the molecular weight of the SLA antigens, SLA-1 and SLA-2. When SLA-positive serum is incubated with the fusion protein according to the present invention, e.g. SLA-1 or SLA-2 fused to another protein or polypeptide, the double band corresponding to the SLA-antigen is not detected. Incubation of SLA-positive sera with a control fusion protein, which does not contain either SLA-1 or SLA-2 does not eliminate the appearance of a double band on Western blots.

[0010] The cDNA according to the present invention allows for the production of large quantities of the SLA antigens in a recombinant fashion. Further, the concentration of SLA antigens can be measured using known SLA auto-antibody methods.

[0011] In another aspect of the invention there is dislcosed a method for determining the presence of SLA auto-antibodies in a blood sample using the composition of the invention in known assay methods such as, but not limited to, radioimmunoassay (RIA), chemiluminescence immunoassay (CIA), immunoblot assay or enzyme immunoassay (EIA). In these assays, one of the SLA antigens (SLA-1 or SLA-2) is bound to a matrix, such as a microtiter plate or a blot membrane. Then the patient's serum to be tested is applied to the matrix with the bound SLA antigen. Following incubation, the test serum is washed off. The specific binding of SLA auto-antibodies (in the test serum) to the matrix-bound SLA-antigen is detected and verified by using a secondary antibody (anti-human immunoglobulin or an immunoglobulin subclass, for example) that has been labeled with a tracer. Tracers commonly used include enzyme compounds such as peroxidase or alkaline phosphatase, radioactive compounds, or a chemiluminescing substances. The more SLA auto-antibodies present in the test serum, the more tracer is bound to the matrix. Normal serum from healthy blood donors can be used as a negative control. Additional controls include the use of SLA auto-antibody positive serum that has SLA auto-antibodies present at known various concentrations.

[0012] Alternatively, an inhibition immunoassay can also be performed using the SLA antigens of the present invention. In such an assay the SLA antigens bind to a selected SLA auto-antibody, which has been labeled with a tracer. The amount of binding of the labeled SLA auto-antibody to the SLA antigens is measured as the control. A patient's sera is then tested against the control. The patient's serum is added along with the labeled SLA auto-antibodies. SLA auto-antibodies present in the patient's serum compete with the labeled SLA auto-antibodies in binding to the SLA antigens. Thus, if the patient's serum contains SLA auto-antibodies, the amount of labeled SLA auto-antibodies present will be less than the control. Therefore the detection of fewer bound labeled SLA auto-antibodies reveals the presence of competing SLA auto-antibodies in the test serum.

EXAMPLE 1

[0013] Detecting SLA Auto-Antibodies in the ELISA Test Using the Recombinant SLA Antigen (SEQ ID No. 1)

[0014] The recombinant SLA antigen was purified using the his-tag. 50 μg of the SLA antigen in 50 μl phosphate buffered saline (“PBS”) (pH 7.0) was placed in a microtiter plate and left over night. After pipetting off and washing the microtiter plate, a post-coating was carried out for one hour using a 1% Bovine Serum Albumin (“BSA”)/PBS solution at room temperature. 50 μl each of normal sera, patients' sera, and control sera were diluted 1:100 with PBS. 50 μl of each diluted serum was incubated for 30 minutes at room temperature on its respective microtiter plate. The plates were then washed 1-5 times and a peroxidase-labeled secondary antibody, an antihuman immunoglobulin, diluted 1:8000 was then added and allowed to incubate. After washing out the excess secondary antibody, ABTS solution [55 mg of 2 2′-azidodi-3-ethyl-benzthiazine-6-sulphonic acid (Serva, Heidelberg) in 5 ml 0.01 M K₂ HPO₄ (pH 6.0), containing 50 μl H₂0₂, diluted in a 1:300 proportion in PBS] was added. The optical density of the microtiter plates was measured with a Titertec Multiscan MC (Flow Laboratories, Meckenheim). Table 1 reveals that all of the patients' sera containing SLA auto-bodies exhibited distinctly elevated values of light absorption, as compared to normal serum, and serum of patients who suffered from other liver diseases. TABLE 1 Serum OD normal serum 1 0.476 normal serum 1 0.471 SLA-serum 1 1.863 SLA-serum 2 1.995 SLA-serum 3 1.791 SLA-serum 4 1.867 AMA-pos. serum (PBC) 0.615 LKM-pos. serum (hep. C) 0.769

[0015]

1 4 1 1335 DNA Homo sapiens CDS (1)...(1335) 1 tcg cgg cgg gag agc ggc tgg tgt cgc cgg ctt acg tgc ggc agg gct 48 Ser Arg Arg Glu Ser Gly Trp Cys Arg Arg Leu Thr Cys Gly Arg Ala 1 5 10 15 gtg agg ccc gcc gct cgc atg agc acc tca tac ggc tgc ttc tgg aga 96 Val Arg Pro Ala Ala Arg Met Ser Thr Ser Tyr Gly Cys Phe Trp Arg 20 25 30 agg ttc att cat ggc att gga cga tcc ggt gat att tct gct gtg caa 144 Arg Phe Ile His Gly Ile Gly Arg Ser Gly Asp Ile Ser Ala Val Gln 35 40 45 cca aaa gct gca ggc tct agc ctt ttg aac aaa att acc aat tct ttg 192 Pro Lys Ala Ala Gly Ser Ser Leu Leu Asn Lys Ile Thr Asn Ser Leu 50 55 60 gtc ctg gac att ata aag ctg gct ggt gtc cat aca gta gcc aac tgc 240 Val Leu Asp Ile Ile Lys Leu Ala Gly Val His Thr Val Ala Asn Cys 65 70 75 80 ttt gta gtt cct atg gca act ggt atg agt cta act ctg tgt ttc tta 288 Phe Val Val Pro Met Ala Thr Gly Met Ser Leu Thr Leu Cys Phe Leu 85 90 95 aca tta cga cac aaa aga cca aag gca aag tat att ata tgg cca cga 336 Thr Leu Arg His Lys Arg Pro Lys Ala Lys Tyr Ile Ile Trp Pro Arg 100 105 110 ata gac cag aag tcc tgc ttt aaa tcc atg atc act gca ggt ttt gag 384 Ile Asp Gln Lys Ser Cys Phe Lys Ser Met Ile Thr Ala Gly Phe Glu 115 120 125 cct gtg gtg ata gaa aat gtt ttg gaa ggt gac gag ctg cgt aca gac 432 Pro Val Val Ile Glu Asn Val Leu Glu Gly Asp Glu Leu Arg Thr Asp 130 135 140 ctg aaa gca gtg gag gct aaa gtc cag gaa ctt ggg cct gat tgc att 480 Leu Lys Ala Val Glu Ala Lys Val Gln Glu Leu Gly Pro Asp Cys Ile 145 150 155 160 ctg tgt att cat tct act aca tcc tgt ttt gct cca agg gtg cct gat 528 Leu Cys Ile His Ser Thr Thr Ser Cys Phe Ala Pro Arg Val Pro Asp 165 170 175 aga tta gaa gaa ctg gct gtg att tgt gct aat tat gac att cca cat 576 Arg Leu Glu Glu Leu Ala Val Ile Cys Ala Asn Tyr Asp Ile Pro His 180 185 190 ata gtt aat aat gct tat gga gtg cag tct tca aag tgt atg cat ctc 624 Ile Val Asn Asn Ala Tyr Gly Val Gln Ser Ser Lys Cys Met His Leu 195 200 205 att cag cag ggg gct cga gtt ggt aga ata gat gct ttt gtt cag agc 672 Ile Gln Gln Gly Ala Arg Val Gly Arg Ile Asp Ala Phe Val Gln Ser 210 215 220 ttg gac aaa aat ttt atg gtt cca gta ggt ggt gct ata att gct ggc 720 Leu Asp Lys Asn Phe Met Val Pro Val Gly Gly Ala Ile Ile Ala Gly 225 230 235 240 ttt aat gat tca ttc att cag gaa atc agc aag atg tat cca gga aga 768 Phe Asn Asp Ser Phe Ile Gln Glu Ile Ser Lys Met Tyr Pro Gly Arg 245 250 255 gct tca gct tca cct tct tta gat gtc ctt att act tta ttg tca ctt 816 Ala Ser Ala Ser Pro Ser Leu Asp Val Leu Ile Thr Leu Leu Ser Leu 260 265 270 gga tca aat ggc tat aag aag cta cta aaa gaa aga aag gaa atg ttt 864 Gly Ser Asn Gly Tyr Lys Lys Leu Leu Lys Glu Arg Lys Glu Met Phe 275 280 285 tca tat ttg tcc aac caa ata aag aag ttg tca gaa gcc tac aat gaa 912 Ser Tyr Leu Ser Asn Gln Ile Lys Lys Leu Ser Glu Ala Tyr Asn Glu 290 295 300 aga ctg ttg cat aca cct cac aat ccc ata tct tta gct atg aca ctt 960 Arg Leu Leu His Thr Pro His Asn Pro Ile Ser Leu Ala Met Thr Leu 305 310 315 320 aaa aca cta gat gaa cac cgt gac aaa gct gtc act cag ctt ggc tcg 1008 Lys Thr Leu Asp Glu His Arg Asp Lys Ala Val Thr Gln Leu Gly Ser 325 330 335 atg ctt ttt acc aaa cag gtt tct gga gcc agg gtt gtg cct ctt ggg 1056 Met Leu Phe Thr Lys Gln Val Ser Gly Ala Arg Val Val Pro Leu Gly 340 345 350 tcc atg caa act gtg agt ggc tat act ttc aga ggc ttt atg tca cat 1104 Ser Met Gln Thr Val Ser Gly Tyr Thr Phe Arg Gly Phe Met Ser His 355 360 365 aca aat aat tac cct tgt gct tac ctc aat gct gca tca gcc atc gga 1152 Thr Asn Asn Tyr Pro Cys Ala Tyr Leu Asn Ala Ala Ser Ala Ile Gly 370 375 380 atg aar atg cag gat gtg gac ctg ttc ata aac ara ctt gac agg tgt 1200 Met Lys Met Gln Asp Val Asp Leu Phe Ile Asn Xaa Leu Asp Arg Cys 385 390 395 400 tta aag gca gta aga aaa gaa cga agt aaa gag agt gat gac aat tat 1248 Leu Lys Ala Val Arg Lys Glu Arg Ser Lys Glu Ser Asp Asp Asn Tyr 405 410 415 gac aaa act gaa rat gtg gat att gaa gaa atg gct tta aaa cta gat 1296 Asp Lys Thr Glu Xaa Val Asp Ile Glu Glu Met Ala Leu Lys Leu Asp 420 425 430 aat gta ctt ctt gac aca tac cag gat gct tct tca tga 1335 Asn Val Leu Leu Asp Thr Tyr Gln Asp Ala Ser Ser * 435 440 2 444 PRT Homo sapiens VARIANT (1)...(444) Xaa = Any Amino Acid 2 Ser Arg Arg Glu Ser Gly Trp Cys Arg Arg Leu Thr Cys Gly Arg Ala 1 5 10 15 Val Arg Pro Ala Ala Arg Met Ser Thr Ser Tyr Gly Cys Phe Trp Arg 20 25 30 Arg Phe Ile His Gly Ile Gly Arg Ser Gly Asp Ile Ser Ala Val Gln 35 40 45 Pro Lys Ala Ala Gly Ser Ser Leu Leu Asn Lys Ile Thr Asn Ser Leu 50 55 60 Val Leu Asp Ile Ile Lys Leu Ala Gly Val His Thr Val Ala Asn Cys 65 70 75 80 Phe Val Val Pro Met Ala Thr Gly Met Ser Leu Thr Leu Cys Phe Leu 85 90 95 Thr Leu Arg His Lys Arg Pro Lys Ala Lys Tyr Ile Ile Trp Pro Arg 100 105 110 Ile Asp Gln Lys Ser Cys Phe Lys Ser Met Ile Thr Ala Gly Phe Glu 115 120 125 Pro Val Val Ile Glu Asn Val Leu Glu Gly Asp Glu Leu Arg Thr Asp 130 135 140 Leu Lys Ala Val Glu Ala Lys Val Gln Glu Leu Gly Pro Asp Cys Ile 145 150 155 160 Leu Cys Ile His Ser Thr Thr Ser Cys Phe Ala Pro Arg Val Pro Asp 165 170 175 Arg Leu Glu Glu Leu Ala Val Ile Cys Ala Asn Tyr Asp Ile Pro His 180 185 190 Ile Val Asn Asn Ala Tyr Gly Val Gln Ser Ser Lys Cys Met His Leu 195 200 205 Ile Gln Gln Gly Ala Arg Val Gly Arg Ile Asp Ala Phe Val Gln Ser 210 215 220 Leu Asp Lys Asn Phe Met Val Pro Val Gly Gly Ala Ile Ile Ala Gly 225 230 235 240 Phe Asn Asp Ser Phe Ile Gln Glu Ile Ser Lys Met Tyr Pro Gly Arg 245 250 255 Ala Ser Ala Ser Pro Ser Leu Asp Val Leu Ile Thr Leu Leu Ser Leu 260 265 270 Gly Ser Asn Gly Tyr Lys Lys Leu Leu Lys Glu Arg Lys Glu Met Phe 275 280 285 Ser Tyr Leu Ser Asn Gln Ile Lys Lys Leu Ser Glu Ala Tyr Asn Glu 290 295 300 Arg Leu Leu His Thr Pro His Asn Pro Ile Ser Leu Ala Met Thr Leu 305 310 315 320 Lys Thr Leu Asp Glu His Arg Asp Lys Ala Val Thr Gln Leu Gly Ser 325 330 335 Met Leu Phe Thr Lys Gln Val Ser Gly Ala Arg Val Val Pro Leu Gly 340 345 350 Ser Met Gln Thr Val Ser Gly Tyr Thr Phe Arg Gly Phe Met Ser His 355 360 365 Thr Asn Asn Tyr Pro Cys Ala Tyr Leu Asn Ala Ala Ser Ala Ile Gly 370 375 380 Met Lys Met Gln Asp Val Asp Leu Phe Ile Asn Xaa Leu Asp Arg Cys 385 390 395 400 Leu Lys Ala Val Arg Lys Glu Arg Ser Lys Glu Ser Asp Asp Asn Tyr 405 410 415 Asp Lys Thr Glu Xaa Val Asp Ile Glu Glu Met Ala Leu Lys Leu Asp 420 425 430 Asn Val Leu Leu Asp Thr Tyr Gln Asp Ala Ser Ser 435 440 3 1491 DNA Homo sapiens CDS (1)...(1491) misc_feature (1)...(1491) n = A,T,C or G 3 tcg cgg cgg gag agc ggc tgg tgt cgc cgg ctt acg tgc ggc agg gct 48 Ser Arg Arg Glu Ser Gly Trp Cys Arg Arg Leu Thr Cys Gly Arg Ala 1 5 10 15 gtg agg ccc gcc gct cgc atg agc acc tca tac ggc tgc ttc tgg aga 96 Val Arg Pro Ala Ala Arg Met Ser Thr Ser Tyr Gly Cys Phe Trp Arg 20 25 30 agg gcw nnn tgt cca aag aat ggc tgg gat gaa agt aca ctt gaa ctc 144 Arg Xaa Xaa Cys Pro Lys Asn Gly Trp Asp Glu Ser Thr Leu Glu Leu 35 40 45 ttt tta cat gaa ctt gca atc atg gac agc aac aat ttc tta ggc aat 192 Phe Leu His Glu Leu Ala Ile Met Asp Ser Asn Asn Phe Leu Gly Asn 50 55 60 tgt ggt gtg gga gaa agg gaa ggg aga gtg gca tcc gca ctg gtt gct 240 Cys Gly Val Gly Glu Arg Glu Gly Arg Val Ala Ser Ala Leu Val Ala 65 70 75 80 cgt cgt cat tac agg ttc att cat ggc att gga cga tcc ggt gat att 288 Arg Arg His Tyr Arg Phe Ile His Gly Ile Gly Arg Ser Gly Asp Ile 85 90 95 tct gct gtg caa cca aaa gct gca ggc tct agc ctt ttg aac aaa att 336 Ser Ala Val Gln Pro Lys Ala Ala Gly Ser Ser Leu Leu Asn Lys Ile 100 105 110 acc aat tct ttg gtc ctg gac att ata aag ctg gct ggt gtc cat aca 384 Thr Asn Ser Leu Val Leu Asp Ile Ile Lys Leu Ala Gly Val His Thr 115 120 125 gta gcc aac tgc ttt gta gtt cct atg gca act ggt atg agt cta act 432 Val Ala Asn Cys Phe Val Val Pro Met Ala Thr Gly Met Ser Leu Thr 130 135 140 ctg tgt ttc tta aca tta cga cac aaa aga cca aag gca aag tat att 480 Leu Cys Phe Leu Thr Leu Arg His Lys Arg Pro Lys Ala Lys Tyr Ile 145 150 155 160 ata tgg cca cga ata gac cag aag tcc tgc ttt aaa tcc atg atc act 528 Ile Trp Pro Arg Ile Asp Gln Lys Ser Cys Phe Lys Ser Met Ile Thr 165 170 175 gca ggt ttt gag cct gtg gtg ata gaa aat gtt ttg gaa ggt gac gag 576 Ala Gly Phe Glu Pro Val Val Ile Glu Asn Val Leu Glu Gly Asp Glu 180 185 190 ctg cgt aca gac ctg aaa gca gtg gag gct aaa gtc cag gaa ctt ggg 624 Leu Arg Thr Asp Leu Lys Ala Val Glu Ala Lys Val Gln Glu Leu Gly 195 200 205 cct gat tgc att ctg tgt att cat tct act aca tcc tgt ttt gct cca 672 Pro Asp Cys Ile Leu Cys Ile His Ser Thr Thr Ser Cys Phe Ala Pro 210 215 220 agg gtg cct gat aga tta gaa gaa ctg gct gtg att tgt gct aat tat 720 Arg Val Pro Asp Arg Leu Glu Glu Leu Ala Val Ile Cys Ala Asn Tyr 225 230 235 240 gac att cca cat ata gtt aat aat gct tat gga gtg cag tct tca aag 768 Asp Ile Pro His Ile Val Asn Asn Ala Tyr Gly Val Gln Ser Ser Lys 245 250 255 tgt atg cat ctc att cag cag ggg gct cga gtt ggt aga ata gat gct 816 Cys Met His Leu Ile Gln Gln Gly Ala Arg Val Gly Arg Ile Asp Ala 260 265 270 ttt gtt cag agc ttg gac aaa aat ttt atg gtt cca gta ggt ggt gct 864 Phe Val Gln Ser Leu Asp Lys Asn Phe Met Val Pro Val Gly Gly Ala 275 280 285 ata att gct ggc ttt aat gat tca ttc att cag gaa atc agc aag atg 912 Ile Ile Ala Gly Phe Asn Asp Ser Phe Ile Gln Glu Ile Ser Lys Met 290 295 300 tat cca gga aga gct tca gct tca cct tct tta gat gtc ctt att act 960 Tyr Pro Gly Arg Ala Ser Ala Ser Pro Ser Leu Asp Val Leu Ile Thr 305 310 315 320 tta ttg tca ctt gga tca aat ggc tat aag aag cta cta aaa gaa aga 1008 Leu Leu Ser Leu Gly Ser Asn Gly Tyr Lys Lys Leu Leu Lys Glu Arg 325 330 335 aag gaa atg ttt tca tat ttg tcc aac caa ata aag aag ttg tca gaa 1056 Lys Glu Met Phe Ser Tyr Leu Ser Asn Gln Ile Lys Lys Leu Ser Glu 340 345 350 gcc tac aat gaa aga ctg ttg cat aca cct cac aat ccc ata tct tta 1104 Ala Tyr Asn Glu Arg Leu Leu His Thr Pro His Asn Pro Ile Ser Leu 355 360 365 gct atg aca ctt aaa aca cta gat gaa cac cgt gac aaa gct gtc act 1152 Ala Met Thr Leu Lys Thr Leu Asp Glu His Arg Asp Lys Ala Val Thr 370 375 380 cag ctt ggc tcg atg ctt ttt acc aaa cag gtt tct gga gcc agg gtt 1200 Gln Leu Gly Ser Met Leu Phe Thr Lys Gln Val Ser Gly Ala Arg Val 385 390 395 400 gtg cct ctt ggg tcc atg caa act gtg agt ggc tat act ttc aga ggc 1248 Val Pro Leu Gly Ser Met Gln Thr Val Ser Gly Tyr Thr Phe Arg Gly 405 410 415 ttt atg tca cat aca aat aat tac cct tgt gct tac ctc aat gct gca 1296 Phe Met Ser His Thr Asn Asn Tyr Pro Cys Ala Tyr Leu Asn Ala Ala 420 425 430 tca gcc atc gga atg aar atg cag gat gtg gac ctg ttc ata aac ara 1344 Ser Ala Ile Gly Met Lys Met Gln Asp Val Asp Leu Phe Ile Asn Xaa 435 440 445 ctt gac agg tgt tta aag gca gta aga aaa gaa cga agt aaa gag agt 1392 Leu Asp Arg Cys Leu Lys Ala Val Arg Lys Glu Arg Ser Lys Glu Ser 450 455 460 gat gac aat tat gac aaa act gaa rat gtg gat att gaa gaa atg gct 1440 Asp Asp Asn Tyr Asp Lys Thr Glu Xaa Val Asp Ile Glu Glu Met Ala 465 470 475 480 tta aaa cta gat aat gta ctt ctt gac aca tac cag gat gct tct tca 1488 Leu Lys Leu Asp Asn Val Leu Leu Asp Thr Tyr Gln Asp Ala Ser Ser 485 490 495 tga 1491 * 4 496 PRT Homo sapiens VARIANT (1)...(496) Xaa = Any Amino Acid 4 Ser Arg Arg Glu Ser Gly Trp Cys Arg Arg Leu Thr Cys Gly Arg Ala 1 5 10 15 Val Arg Pro Ala Ala Arg Met Ser Thr Ser Tyr Gly Cys Phe Trp Arg 20 25 30 Arg Xaa Xaa Cys Pro Lys Asn Gly Trp Asp Glu Ser Thr Leu Glu Leu 35 40 45 Phe Leu His Glu Leu Ala Ile Met Asp Ser Asn Asn Phe Leu Gly Asn 50 55 60 Cys Gly Val Gly Glu Arg Glu Gly Arg Val Ala Ser Ala Leu Val Ala 65 70 75 80 Arg Arg His Tyr Arg Phe Ile His Gly Ile Gly Arg Ser Gly Asp Ile 85 90 95 Ser Ala Val Gln Pro Lys Ala Ala Gly Ser Ser Leu Leu Asn Lys Ile 100 105 110 Thr Asn Ser Leu Val Leu Asp Ile Ile Lys Leu Ala Gly Val His Thr 115 120 125 Val Ala Asn Cys Phe Val Val Pro Met Ala Thr Gly Met Ser Leu Thr 130 135 140 Leu Cys Phe Leu Thr Leu Arg His Lys Arg Pro Lys Ala Lys Tyr Ile 145 150 155 160 Ile Trp Pro Arg Ile Asp Gln Lys Ser Cys Phe Lys Ser Met Ile Thr 165 170 175 Ala Gly Phe Glu Pro Val Val Ile Glu Asn Val Leu Glu Gly Asp Glu 180 185 190 Leu Arg Thr Asp Leu Lys Ala Val Glu Ala Lys Val Gln Glu Leu Gly 195 200 205 Pro Asp Cys Ile Leu Cys Ile His Ser Thr Thr Ser Cys Phe Ala Pro 210 215 220 Arg Val Pro Asp Arg Leu Glu Glu Leu Ala Val Ile Cys Ala Asn Tyr 225 230 235 240 Asp Ile Pro His Ile Val Asn Asn Ala Tyr Gly Val Gln Ser Ser Lys 245 250 255 Cys Met His Leu Ile Gln Gln Gly Ala Arg Val Gly Arg Ile Asp Ala 260 265 270 Phe Val Gln Ser Leu Asp Lys Asn Phe Met Val Pro Val Gly Gly Ala 275 280 285 Ile Ile Ala Gly Phe Asn Asp Ser Phe Ile Gln Glu Ile Ser Lys Met 290 295 300 Tyr Pro Gly Arg Ala Ser Ala Ser Pro Ser Leu Asp Val Leu Ile Thr 305 310 315 320 Leu Leu Ser Leu Gly Ser Asn Gly Tyr Lys Lys Leu Leu Lys Glu Arg 325 330 335 Lys Glu Met Phe Ser Tyr Leu Ser Asn Gln Ile Lys Lys Leu Ser Glu 340 345 350 Ala Tyr Asn Glu Arg Leu Leu His Thr Pro His Asn Pro Ile Ser Leu 355 360 365 Ala Met Thr Leu Lys Thr Leu Asp Glu His Arg Asp Lys Ala Val Thr 370 375 380 Gln Leu Gly Ser Met Leu Phe Thr Lys Gln Val Ser Gly Ala Arg Val 385 390 395 400 Val Pro Leu Gly Ser Met Gln Thr Val Ser Gly Tyr Thr Phe Arg Gly 405 410 415 Phe Met Ser His Thr Asn Asn Tyr Pro Cys Ala Tyr Leu Asn Ala Ala 420 425 430 Ser Ala Ile Gly Met Lys Met Gln Asp Val Asp Leu Phe Ile Asn Xaa 435 440 445 Leu Asp Arg Cys Leu Lys Ala Val Arg Lys Glu Arg Ser Lys Glu Ser 450 455 460 Asp Asp Asn Tyr Asp Lys Thr Glu Xaa Val Asp Ile Glu Glu Met Ala 465 470 475 480 Leu Lys Leu Asp Asn Val Leu Leu Asp Thr Tyr Gln Asp Ala Ser Ser 485 490 495 

We claim:
 1. A composition for detecting the presence of SLA auto-antibodies in a patient's blood serum, comprising an antigen that is recognized by SLA auto-antibodies.
 2. The composition of claim 1 wherein said antigen is selected from the group consisting of antigens having amino acid sequence SEQ ID NO. 1, SEQ ID NO. 2, and antigenic derivatives thereof.
 3. The composition of claim 2 wherein said antigen consists of amino acid sequence SEQ ID NO. 1 or an antigenic derivative thereof.
 4. The composition of claim 2 wherein said antigen consists of amino acid sequence SEQ ID NO. 2 or an antigenic derivative therof.
 5. The composition of claim 2 wherein said antigen is a purified polypeptide selected from the group consisting of polypeptides having amino acid sequence SEQ ID NO. 1, SEQ ID NO. 2, antigenic derivatives of SEQ ID NO. 1, antigenic derivates of SEQ ID NO. 2, fusion protein containing SEQ ID NO. 1, fusion protein containing SEQ ID NO. 2, and fusion protein containing antigenic derivatives of SEQ ID NO. 1 or SEQ ID NO.
 2. 6. The purified polypeptide of claim 5 wherein said polypeptide consists of amino acid SEQ ID NO. 1 or an antigenic derivative thereof.
 7. The purified polypeptide of claim 5 wherein said polypeptide consists of amino acid SEQ ID NO. 2 or an antigenic derivative thereof.
 8. A cDNA comprising a nucleotide sequence that codes for an antigen recognized by SLA auto-antibodies in blood serum.
 9. The cDNA of claim 8 wherein said cDNA codes for an antigen having the amino acid sequence SEQ ID NO. 1, SEQ ID NO. 2, or antigenic derivates thereof.
 10. The cDNA of claim 9 wherein said cDNA codes for an antigen having the amino acid sequence SEQ ID NO. 1 or an antigenic derivative thereof.
 11. The cDNA of claim 9 wherein said cDNA codes for an antigen having the amino acid sequence SEQ ID NO. 2 or an antigenic derivative thereof.
 12. A method of detecting the presence of SLA auto-antibodies in a patient's blood serum comprising binding an antigen that is recognized by SLA auto-antibodies to a matrix, detecting binding of said SLA auto-antibodies to said antigen, and correlating said binding to the presence of SLA auto-antibodies in the patient's blood serum.
 13. The method of claim 12 wherein the method is an immunoassay selected from the group consisting of radioimmunoassay, chemiluninesence immunoassay, immunoblot assay, enzyme assay and inhibition immunoassay.
 14. The method of claim 12 wherein said antigen has the amino acid sequence SEQ ID NO. 1, SEQ ID NO. 2, or antigenic derivatives thereof.
 15. The method of claim 12 wherein said antigen has the amino acid sequence SEQ ID NO. 1 or an antigenic derivative therof.
 16. The method of claim 12 wherein said antigen has the amino acid sequence SEQ ID NO. 2 or an antigenic derivative thereof.
 17. The method of claim 12 wherein the antigen comprises a fusion protein. 